In the large-scale generation of electricity a considerable quantity of low-pressure steam frequently results and this steam must be condensed. Since the energy of the steam is extremely low it is mere condensation that is sufficient, no consideration need be given to recovering some of the energy from the steam.
Thus it is common practice simply to pass the steam upwardly in a scrubbing tower. Water, usually derived from a river, lake, or the like, is sprayed downwardly contercurrent to the rising column of steam so as to condense this steam. Such a system has the considerable disadvantage that a relatively large and complicated installation is necessary. Furthermore a relatively low efficiency is obtained because it is necessary to operate this condensing tower with a relatively small gas head, since any back pressure in the condensing tower would adversely effect the operation of the upstream gas turbines for electric generating.